A great little place. Can't get any more authentic Spanish than this, and they have a good selection of stuff from South America.
As the name suggests, they have a library of Spanish-language books/magazines in the back.
By far tthe highlight of my visits is the fact that they often (but not always) stock alfajores from the Havana chain of cafes. These Argentine delights are made with cookies, dulce de leche, covered in chocolate or meringue.